Method for immediately placing a non-occlusive dental implant prosthesis

ABSTRACT

A method for immediately placing a non-occlusive and non-functional temporary dental implant prosthesis in the jawbone of a human patient with the prosthesis having a size and shape of a natural human tooth.

This is a continuation-in-part of U.S. application Ser. No. 09/755,240,filed on Jan. 5, 2001 now U.S. Pat. No. 6,368,108, invented by Robert L.Riley, et al., and entitled “Method for Immediately Placing aNon-occlusive Dental Implant Prosthesis.”

FIELD OF THE INVENTION

The present invention relates generally to a method for immediatelyplacing a non-occlusive and non-functional temporary dental implantprosthesis in the jawbone of a human patient wherein the prosthesis hasa size and shape of a natural human tooth.

BACKGROUND OF THE INVENTION

Numerous surgical techniques and methods currently exist to install adental implant and prosthesis into the jawbone of a human patient.During a conventional surgical procedure, an incision is made along thegingival tissue at the implant site of the patient, a cylindrical boreis drilled into the alveolar bone, and the bore of the bone is tapped.Once the bore is fully prepared, a dental implant is positioned abovethe implant site and driven into the bore. A healing screw or healingcap is then placed on the coronal end of the implant, and the gingivaltissue is sutured. The implant and healing cap remain within the bonefor several months as osseointegration and healing occur. After thishealing period, a second surgical procedure begins. During thisprocedure, the gingival tissue is again cut, the implant is re-exposed,and the healing cap is removed. Thereafter, an abutment is affixed ontothe top of the implant and a dental prosthesis is affixed to theabutment.

This conventional surgical procedure has many disadvantages. First,during the healing stage while the implant integrates into the bone, atooth or dental prosthesis will not be present at the implantation site.The patient may have an unsightly gap or otherwise unaestheticappearance at this location. Further, in some instances, a metallichealing cap or metallic gingival cuff may be left attached to theimplant while the tissue and bone heal. The cap and cuff are oftenvisibly exposed in the mouth of the patient and present an unnaturalappearance. Further yet in conventional techniques, the patient has toundergo two separate surgical procedures: an initial procedure toimplant the implant and a second procedure to remove the healing cap andattach the abutment and prosthesis. Multiple surgical procedures arecostly and not desirable for the patient.

Some dental implant systems and surgical techniques attempt to solve thedisadvantages associated with conventional implantation procedures.These systems place a prosthetic tooth in occlusion immediately afterthe implant is driven and positioned in the jawbone of the patient. Inthis scenario, the patient has a tooth-like prosthesis immediately afterthe surgery, so aesthetic appearance is no longer a concern. Theprosthesis, however, is left in occlusion and thus exposed to immediateloads.

This procedure has disadvantages too. Preferably, movement anddisturbance of the implant should be minimal immediately after it isplaced in the jawbone. If the prosthesis and attached implant experienceloading too soon, then the position of the implant may rotate, loosen,or otherwise move. Such movement could adversely effect the integrationand alignment of the implant.

U.S. Pat. No. 5,967,783 (entitled “Threaded Dental Implant with a Coreto Thread Ration Facilitating Immediate Loading and Method ofInstallation”) illustrates a dental implant system designed toimmediately place and then load a dental prosthesis. As shown in FIG. 1,an implant 10 consists of an elongated unitary body having a mainimplant portion 12 with external threads 14 and an extended neck portion16. One disadvantage to this system is that the implant has an elongatedimplant and neck portions formed from a single piece. A clinician may berequired to perform significant modifications to the extended neckportion so it has the correct height or angle to receive the prosthesis.Further, the neck portion could not easily accommodate a screw-retainedprosthesis, especially if the neck needed extensive modification.Further yet, the implant is loaded immediately after it is placed; andsuch loads, as discussed above, may move the implant or otherwiseinterfere with its orientation or integration. The external threads 14on the implant further have a specific and specialized thread pattern tohelp improve resistance of the implant to chewing and compressiveforces. This specialized thread pattern may add additional cost to theimplant.

The present invention solves the problems discussed with prior methodsand dental delivery systems and provides numerous advantages over theseprior systems and methods.

SUMMARY OF THE INVENTION

The present invention is directed toward a method for placing anon-occlusive, non-functional temporary dental implant prosthesisimmediately after a dental implant is implanted into the jawbone of ahuman patient. The implant is placed in a conventional manner foredentulous or extraction dental implantation sites. Thereafter, in oneembodiment, a separate abutment is connected to the implant; typicallysuch a connection occurs with a screw or cement. A temporary dentalimplant prosthesis is then attached to the abutment. Most importantly,the temporary prosthesis is placed to be non-occlusive andnon-functional; that is to say loads and compressive forces are nottransmitted to the implant during normal mastication.

The present method has numerous advantages over prior methods. First, atooth-shaped temporary prosthesis is connected to implant immediatelyafter the implant is implanted into the jawbone of the patient. As such,the patient does not have an unsightly gap or otherwise unaestheticappearance at the implantation site. Further, a second, separatesurgical procedure is not required since the implant, abutment, andtemporary prosthesis are all placed during the first surgical procedure.Further yet, since the prosthesis is left out of occlusion, it is notexposed to immediate loads. Thus, movement and disturbance of theimplant is minimized during the integration period. Further yet, theimplant and abutment are made from two separate pieces, and the implantis not required to have a special external thread design to help improveresistance of the implant to chewing and compressive forces.

In another embodiment, the prosthesis is formed from an internalmetallic core and an external ceramic crown. The crown has a shape thatclosely resembles the shape of a natural human tooth. The prosthesis canbe placed directly on the implant in one step, leaving the patient witha temporary prosthesis that resembles a natural human tooth.

This near net tooth shape of the crown will reduce the amount of work,time, and expense required to create a final dental prostheticrestoration. Further, the ceramic used to fabricate this crown iscompatible with commercially available porcelains so that the gradientsof shade and translucence of the natural tooth can be replicated. Also,the crown may be manufactured to have a size that is slightly smallerthan the average natural tooth. This difference in size enables thecrown to receive an additional layer of porcelain and then match theexact size of the natural tooth.

As another advantage, the prosthetic teeth of the present invention maybe manufactured and sold as a kit. Each kit would include a plurality ofprosthetic teeth having different sizes and shapes emulating differentsizes and shapes of natural human teeth. A clinician could chose aprosthetic tooth to best match particular needs of a patient.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will hereafter be described with reference to theaccompanying drawings:

FIG. 1 is a side-view, partially in cross section, of a prior art dentalimplant system.

FIG. 2 is a block diagram illustrating the method of the presentinvention.

FIGS. 3A-3C show a dental implant, abutment, and temporary prosthesisbeing implanted according to the method of the present invention.

FIG. 4 is a cross-sectional side view illustrating an embodiment of adental prosthetic assembly according to one embodiment of the invention.

FIG. 5 is an exploded cross-sectional side view illustrating anembodiment of a dental prosthetic assembly.

FIG. 6 is a perspective view illustrating an embodiment of a coremember.

FIG. 7 is a perspective view illustrating another embodiment of a coremember.

FIG. 8 is a side-view illustrating an embodiment of a near net toothshaped crown.

FIGS. 9a-9 e are views illustrating a plurality of tooth shapes for thenear net tooth shaped crown.

FIG. 10 is a cross-sectional side view illustrating an embodiment of athreaded attachment of a near net tooth shaped crown and a core member.

FIG. 11 is a cross-sectional side view illustrating another embodimentof a dental prosthetic assembly.

FIG. 12 is a cross-sectional view of an embodiment of a core with atapered outside diameter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning to FIG. 2 and FIGS. 3A-3C, the method of the present inventionis discussed in detail. Per block 20 of FIG. 2, the invention may beutilized with both edentulous sites and extraction sites. Further, suchsites may be single or multiple restorations. For illustrative purposes,the figures and accompanying description teach application of thepresent invention to a single tooth extraction implantation site.

As shown in block 22, initially the implantation site is evaluated andprepared. Preferably, the site maintains a gentle elevation of the toothroot to preserve the alveolar housing around the extraction site. Aperiotome or other small elevators (not shown) may be used to releasethe periodontal ligament or other soft tissue attachment of the tooth tothe surrounding bone. Once the tooth is removed, the socket site shouldbe debrided to remove any soft tissue remnants and then irrigated withsterile saline. A visual inspection of the site can aid in determiningthe appropriate diameter implant.

As shown in block 24, the next step is to place the implant into theimplantation site 31 (shown in FIGS. 3A-3C). Various implants may beplaced using any one of numerous techniques known to those skilled inthe art. Preferably, the implant should be dimensioned to sufficientlyfill the entire cervical region of the socket. Further, properorientation and location of the receptor site may be predicated on theinitial step of scoring the apex of the socket with a bur or similarinstrument. Such scoring provides a recess in the bone 32 to guide apilot drill (not shown) to a correct, predetermined location.

One example of an implant appropriate for the method of the presentinvention is a Spline Twist MP-1 implant, manufactured by SulzerCalcitek Inc. of Carlsbad, Calif. In this instance, the implant 34 canbe delivered to the implantation site and inserted via a handpiece andratchet (not shown). The platform for this implant preferably is placedapproximately 1.5 mm below the interproximal bone 36 and below thegingival tissue 38. Placement in this location helps to ensure that theexternal threads on the implant will be covered by bone and will be ator below the buccal plate.

After the implant is placed, bone grafting may be required. In thisinstance, a cover screw may be temporarily secured onto the proximal endof the implant to prevent any particulate graft from entering theinternal chamber of the implant. Once grafting is completed, the coverscrew is removed.

As shown in block 26, the next step is to place an abutment 40 onto theimplant. The abutment should be separate from the implant andconnectable to the implant using screws, cement, or other techniquesknown to those skilled in the art. One advantage of having a separateabutment is that various cuff heights and angles may be selected toclosely replicate the desired height, angles, and profiles needed. Inthis manner, the amount of alterations to the abutment is minimized. Ofcourse, the abutment can be modified to meet clinical needs, such as amodification to the overall height or cuff contour.

As shown in block 28, the next step is to place a temporary,non-functional prosthesis 42 on the abutment 40. One important aspect ofthe present invention is that the prosthesis must be placed in anon-functional or non-occlusive position. Preferably, a top portion 44of the prosthesis is placed between 0.5 mm and 2 mm below a top 46 ofadjacent teeth, as shown in FIG. 3C. In this position, the prosthesis 42will not be in occlusal loading during the healing period. As such, theprosthesis should be taken completely out of occlusion when the patientis in centric relations and lateral excursions.

After a verification is made that no occlusal loading is present, theprosthesis may be polished and seated with cement or a screw, forexample. The patient should be instructed to avoid chewing in theimplantation area of the prosthesis while the implant is allowed toheal. Typically, the healing period will occur from about one month toabout nine months.

As one important advantage of the method of the present invention,gingival tissue should be contoured around the temporary prosthesis tomaintain a natural shape and appearance. Gingival tissue, for instance,can be sutured around a cervical portion 48 of the prosthesis (as shownin FIG. 3C) if the implantation site is edentulous and an incision wasmade to expose the bone. Suturing the tissue in this manner helps tomaintain and develop soft tissue contours around the prosthesis.Suturing, though, may not be necessary if the implantation site is froman extraction and the abutment and temporary prosthesis completely fillthe hole left from the natural tooth.

As yet another important advantage of this method, hard and soft tissuecontours adjacent to the implant and prosthesis should be maintained toretain interdental papilla 50.

As shown in block 30, after the healing period has elapsed, thetemporary prosthesis is removed from the abutment and a permanentprosthesis is connected. The permanent prosthesis is functional and inocclusion in the jawbone of the patient. An experimental trial wasconducted on a small group of patients to determine the feasibility of amethod in accordance with the present invention. The method was used on55 patients: 19 males and 36 females. The ages of the males ranged from2655 years and females from 17-78 years. All implants were placed fromthe premolar forward. In the male group, one implant was lost due totrauma. In the female group, one implant was mobile after six weeks andrequired removal. The male patient was removed from the combine groupresulting in a total of 54 patients. Survival rate was approximately98.15%.

Based on analysis of the patients in this trial, the method of thepresent invention appears to be a very efficacious for replacing missinganterior teeth. Further evaluation is being conducted in a largerpopulation of patients but shows dramatic promise for the effectivereplacement of lost anterior teeth. This technique has not been employedto posterior teeth beyond the second premolar. It may be effective inthese regions as well; however, the increased occlusal force andprotection factors must be considered. The following two cases areexamples from the experimental trial.

CASE I

A 74-year old female had a fractured, non-salvageable first premolar.The tooth was gently elevated, keeping the soft tissue and hard tissuecontours intact. There was no elevation of the soft tissue. The socketsite was checked to make sure the buccal plate was intact. Directvisualization and palpation were used to identify the inter-septalbuccal plate rim. In this case, the site was prepared via harvestinstrumentation. The platform of the implant was set approximately 1-1.5mm below the level on the inter-septal bone; such placement ensured theshoulder of a 2 mm abutment to be approximately 1 mm below the level ofgingival cuff rim. This placement also ensured that the soft tissuewould be supported to maintain its position and would allow for maximumemergence of the temporary prosthesis (or provisional). The temporaryprosthesis was seated with temporary cement and taken out of occlusion.It was then allowed to heal for 16 weeks. After the healing period, thispatient was then sent to another doctor for fabrication of the finalrestoration. The position of the papilla was maintained as well as thatof the buccal gingival contour, allowing for maximum tissue estheticsand excellent emergence profile.

CASE II

A 47-year old man had tooth #9 that was super-erupted and mobile. Due tohis present occupation, aesthetics and a quick remedy were necessary.The tooth was atraumatically removed and the socket site debrided. Theposition and loss of the gingiva in relation to the adjacent teeth wasimportant here. The implantation site was prepared in a sequentialfashion, utilizing drills and hand instrumentation. The implant was thenseated in place, positioning the platform approximately 1-1.5 mm belowthe level of crestal bone. Here, the width of the socket determined thediameter of the implant, and care was taken not to perforate the buccalplate. The abutment was seated to place, the shoulder beingapproximately 1 mm below the crest of the gingival collar. The temporaryprosthesis was placed and positioned to be out of centric occlusion andexcursive movement. The tissue and implant was allowed to heal. Afterthe normal healing time had transpired, the implant was restored.

The experimental trial demonstrates numerous advantages to the method ofthe present invention. First, the patient does not need to wear aremovable prosthesis during the healing period. Second, the patientleaves the implantation procedure with a fixed provisional prosthesis ortooth. This fact alleviates any apprehension that the patient may haveabout the loss of anterior teeth and provides an esthetically pleasingoption. Third, preservation of the implantation site's soft and hardtissue contours are maintained, improving the esthetics of the temporaryand permanent prostheses. This preservation also allows for the finalrestoration of soft tissue such that no sutures are required at thesurgical site. Further, the patient receives a temporary prosthetictooth the same day as surgery, and no unsightly gaps or unnaturalappearances occur in the mouth of the patient at the implantation site.

Blocks 24 and 26 in FIG. 2 discuss an abutment and prosthesis placed onthe implant in two separate steps. In an alternate embodiment of thepresent invention, these steps may be combined. The abutment andprosthesis may be pre-connected and placed on the implant in one step.Further, regardless whether the abutment and prosthesis arepre-connected or separate, the prosthesis may be manufactured to have atooth shape. These alternate embodiments are discussed below.

FIGS. 4 and 5 show a tooth-like prosthesis 110 having a near net toothshaped crown 112 and a metallic core 116. The crown 112 has an internalbore 114 to receive the core and is manufactured to have a size andshape of a natural human tooth.

As shown, a threaded fastener or screw 120 connects the core 116 to theanchor 118. The fastener includes a first end 120 a having threads 122and a second end 120 b having a polygonal socket 124. A tool (not shown)can be inserted into socket 124 to turn fastener 120 into threadedengagement with a threaded bore 119 in anchor 118. Core 116 includes ascrew bore 126 and a screw seat 128.

Screw bore 126 includes an axis C that extends substantially co-axiallywith an axis A of anchor 118. Fastener 120 is inserted through core 116and threaded into anchor 118. When fully seated, a shoulder 117 ofsecond end 120 b of threaded fastener 120 is seated on screw seat 128within core 116. Further, an axis B passes through the near net crown112 from an incisal edge 112 i to a cervix 112 k.

In FIG. 5, all axes (A, B, and C) are longitudinal and co-axial. Inanother embodiment of the invention, the crown, however, may be angledto provide proper alignment or angular correction of the prosthesis inthe jawbone of the patient. Axis B, for example, could be canted orangled to provide angular offset for the crown.

The core 116 is preferably formed of a material selected for fatiguestrength suitability such as a metal, like titanium or titanium alloy.The metal core can be fabricated with various shapes, such as acylindrical geometry (shown in FIG. 6) or a frusto-conical geometry(shown in FIG. 7). Further, the core may be formed from one piece (asshown in FIG. 4, for example) or formed from two or more pieces. FIG. 4shows a core formed from two pieces: a core body 116 a and a core cuff116 b.

Preferably, the core anti-rotationally engages the implant. Theanti-rotational engagement between the core and implant may occur withnumerous techniques known to those skilled in the art. Some examples ofthese techniques include male and female polygonal projections orlocking tapers. FIGS. 4 and 5 show a spline connection between the coreand implant. In this connection, a plurality of splines 116 c on thecore engage a plurality of mating splines 118 a on anchor 118.

The outer surface of the core may have various textures, coatings, andconfigurations. FIG. 6, for example, shows core 116 with a texturedcoating 116 e on the outer surface. FIG. 7 shows core 116 having aplurality of grooves 116 d. The various textures and coatings canenhance the strength of connection between the core and crown.

While ceramics can be strong, they are often brittle. The addition of ametallic core adds strength to the overall assembly. This added strengthis especially important at the implant interface where forces aretransferred from the restoration to the anchoring implant.

Crown 112, FIG. 8, is formed of an aesthetic suitable material, such asa ceramic material, an unfired ceramic material, a polymer material, ora combination of ceramic and polymer materials. Preferably, the crown ismade from a ceramic, such as aluminum oxide, zirconium oxide, or acomposite thereof. These materials can be made to have mechanicalstrength sufficient to support occlusal forces and are relatively inertwhen exposed to body fluid and tissues. These materials also allow forthe addition of porcelain to their surface to provide shading to theunique color of the adjacent natural dentition. A clinician, laboratory,or the like may add a layer of porcelain to the outer surface of thecrown to match the aesthetics of adjacent natural teeth. The crown canalso be manufactured and sold with a thin layer of porcelain 112 balready applied to its surface. This latter application facilitatesminor modifications to the final prosthetic restoration.

In one embodiment, the crown may be manufactured to have a size that isslightly smaller than the average natural tooth. For example, the crowncan be manufactured to have an outside surface or outside diameter thatis 0.5 mm to 1.5 mm smaller than the natural tooth to be replaced. Thisdifference in size enables the crown to receive an additional layer ofporcelain and then match the exact size of the natural tooth.

One important advantage of the present invention is that the crown ismanufactured to have shapes approximately equal to the natural shapes ofhuman dentition. The crowns, manufactured in these shapes are thusprefabricated and sold to clinicians, laboratories, and the like in theshape of human teeth. Since ceramic materials are typically difficult toshape using machining techniques, the present invention significantlyreduces or completely eliminates the amount of machining required tocreate the shape and size of the final prosthetic restoration.

Crown 112 may be provided in a kit to have a plurality of differentsizes and shapes that mimic the sizes and shapes of natural human teeth.These shapes, for example, could include tooth shapes such as an incisor112 c, FIGS. 9a, 9 b, a canine 112 d, FIG. 9c, a premolar 112 e, FIG. 9dand a molar 112 f, FIG. 9e.

Crown 112 may be attached to core 16 by various means known to thoseskilled in the art. In FIG 4, the bore 114 in the ceramic crown 112 ismade slightly larger than the outside diameter of the core 116. Thisdifference in size creates a cement gap 127. The cement gap is a spacefor dental cement that holds the crown to the core. In FIG. 10, analternative connection method is shown, a threaded fastener 130, such asa set screw, is used to attach crown 112 to core 116.

FIGS. 11 and 12 show another embodiment of the present invention and inparticular illustrate an alternative way to attach crown 112 to core116. A layer of material 129 is provided between the crown and the core.This material is suitable for bonding the two components when thecomponents are heated. This layer of material may be a heat activatedadhesive or may be formed from precious metals, such as gold, silver,platinum, palladium, or alloys formed from these metals.

In the preferred embodiment, the core is fabricated from gold (or a goldalloy) and then gold (or a gold alloy) is used to bond the core and thecrown. Gold is advantageous since it is both strong and biocompatible.Further, dental gold alloys are capable of withstanding highertemperatures than titanium.

Preferably, the gold is applied to the inner bore in the crown. The goldcore and crown are then connected together, and heat is applied to bondthem permanently together. The bonding may occur after an outer layer ofporcelain is applied to the crown and subsequently heated or baked tobond the porcelain to the ceramic crown. This latter step often occurssince dental laboratories bake shades of porcelain onto the ceramiccrown to match color of natural teeth. The heat during this operationmelts or activates the layer of material 129. After the prosthesis isheated, the porcelain baked, and the crown and core bonded, theprosthesis is ready to be implanted into the jawbone of the patient. Asshown in FIGS. 11 and 12, a hole 121 may be left in the crown to provideaccess to the screw 120.

Gold soldering or a brazing process can be used to join the core to thecrown. A dental laboratory, for example, can add the soldering orbrazing gold, or the gold can be supplied as a preform coating installedduring the manufacturing stage. The preform coating can also be addedusing an electroplating process that metallizes the surface of theinternal bore and bonds the crown and core.

What is claimed is:
 1. A method for placing a temporary dentalprosthesis in the jawbone of a human patient, the method comprising thesteps of: implanting a dental implant into the jawbone of the patient;providing a temporary prosthesis having an internal metallic core and anexternal ceramic crown, wherein the temporary prosthesis isprefabricated to have an anatomical size and shape of a natural humantooth; connecting the temporary prosthesis to the implant such that thetemporary prosthesis is in a non-occlusive and non-functional position;leaving the temporary prosthesis connected to the implant for a healingperiod between one and nine months; removing the temporary prosthesisafter the healing period; and replacing the temporary prosthesis with apermanent prosthetic tooth that is in an occlusive and functionalposition in the jawbone.
 2. The method according to claim 1 furthercomprising the step of providing the temporary prosthesis to have aprefabricated shape selected from one of incisor, canine, premolar, ormolar.
 3. The method according to claim 2 wherein the temporaryprosthesis has a color of human teeth.
 4. A method for placing a dentalprosthesis in the jawbone of a human patient, the method comprising thesteps of: implanting a dental implant into the jawbone of the patient;providing a temporary prosthetic tooth having an internal metallic coreand an external ceramic crown, wherein the temporary prosthetic tooth isprefabricated to have an anatomical size and shape of a natural humantooth; connecting the temporary prosthetic tooth to the implant;positioning the temporary prosthetic tooth in a non-occlusive andnonfunctional position in the jawbone; leaving the temporary prosthetictooth connected to the implant for a period between one and nine months;and removing the temporary prosthetic tooth and replacing it with apermanent prosthetic tooth that is in an occlusive and functionalposition in the jawbone.
 5. The method according to claim 4 in which atop of the temporary prosthetic tooth is positioned between 0.5 mm and 2mm below a top of adjacent teeth.
 6. The method according to claim 5 inwhich no loading occurs on the temporary prosthetic tooth when thepatient is in centric relations and lateral excursions.
 7. The methodaccording to claim 4 in which no loading occurs on the temporaryprosthetic tooth during mastication by the patient.